2016—2019年长江口海域季节性低氧对大型底栖动物群落的影响          下载免费PDF全文

贾海波  柴小平  黄备 《海洋学研究》2021,39(2):80-88

基于2016—2019年夏季在长江口海域进行的4个航次的生态环境调查,分析了长江口海域季节性低氧对大型底栖动物群落结构的影响。结果表明,2016—2019年长江口海域夏季底层DO最低值为1.51 mg/L,存在不同程度的底层低氧现象。低氧区与非低氧区之间大型底栖动物的种类数量、丰度、生物量和群落结构均存在显著差异。多毛类表现出对低氧较强的耐受能力,为低氧区的主要优势类群,中蚓虫(Mediomastus sp.)、索沙蚕(Lumbrinereis sp.)为低氧区的主要优势种。软体动物、甲壳动物和棘皮动物的分布趋势则与多毛类相反,其中甲壳动物对低氧的耐受能力较弱。MDS多维尺度排序表明,低氧区与非低氧区之间大型底栖动物的群落组成差异明显;CCA分析表明,长江口海域夏季底层低氧已对大型底栖动物的群落结构产生一定程度的影响。  相似文献   

PCPA致大鼠NG2细胞的变化，NG2与GABA的共存关系及酸枣仁汤的干预作用研究          下载免费PDF全文

滕柳  郭海波  石鹏 《应用海洋学学报》2021,37(4):154

目的：探讨大鼠脑内五羟色胺（5-HT）含量下降后皮质部分NG2细胞的变化,NG2细胞与星形胶质细胞（Ast）、γ-氨基丁酸（GABA）的共存关系及酸枣仁汤的干预作用。方法：根据随机数字表法将雄性SD大鼠分为7 d正常组、7 d对照组、7 d对氯苯丙氨酸（PCPA）组、15 d正常组、15 d对照组、15 d PCPA组、酸枣仁汤（SZRD）组、PCPA+SZRD组,各组大鼠给予相应处理。取大脑皮质前额叶,采取免疫荧光双染法测定大鼠皮质NG2细胞、胶质纤维酸性蛋白（GFAP）、GABA的表达量及NG2/GFAP、NG2/GABA共存定位情况。结果：与7 d对照组比较,7 d PCPA组大鼠皮质NG2细胞、GFAP蛋白表达量增加（P<0.01）,GABA蛋白表达量下降（P<0.05）;与15 d PCPA组比较,PCPA+SZRD组大鼠皮质NG2细胞、GFAP蛋白表达量下降（P<0.01）,GABA表达量上升（P<0.05）;NG2细胞与GABA在同一区域表达较多,而与GFAP在同一区域表达较少。结论：5-HT系统的失调能激活皮质NG2细胞、Ast,抑制GABA的表达,NG2细胞可能与Ast、GABA共同影响大脑皮层兴奋性来调节睡眠,酸枣仁汤可能通过5-HT系统调控NG2细胞、Ast、GABA来参与皮层活动的神经调节。  相似文献   

大陆古海洋学的特点、研究思路和方法——以东昆仑中段纳赤台岩群蛇绿混杂岩构造古地理恢复为例     

蔡雄飞  魏启荣  王岸  王浩霖  罗中杰 《矿物岩石地球化学通报》2010,29(1):98-106

大陆古海洋学是指现代大陆上已消失了的古海洋研究,也可称为造山带古海洋学。实践表明,传统方法无法恢复大陆古海洋;因为造山带古海洋内部已经失序和移位。它的工作方法以反序研究方法为主,从现存的岩石组合(块)的物态、时态(时序)、相态(相序)、位态(位序)和变形、变质调查入手,追寻其原始生成环境、时空结构和变位、变形和变质历程,尽可能还原其本来面目。本文以东昆仑中段纳赤台岩群蛇绿混杂岩构造古地理的恢复为例,指出反序法最具针对性,是大陆古海洋研究不可缺少的工作思路和研究方法。  相似文献   

粤东四望坪铜矿区地质特征及成矿模式     

古润平  卜安 《华南地质与矿产》2010,(2):23-28

以岩浆期后热液交代充填成矿为特征的广东潮安四望坪铜矿床,在其三位一体(岩浆岩、断裂/层间滑动破碎带、围岩)的控矿组合中,以流纹斑岩、晶屑凝灰岩的层间滑动破碎带为最佳。本文从矿区资料的综合研究入手,深入剖析了岩浆岩、断裂、围岩圈闭条件与矿体规模、富集程度的关系。通过对矿区地质环境与矿床成因的深入分析,建立了火山期后热液矿床的控矿模型,为粤东火山岩地区继续寻找该类矿床提供了启示。  相似文献   

The POINT-AGAPE survey – II. An unrestricted search for microlensing events towards M31     

V. Belokurov  J. An  N. W. Evans  P. Hewett  P. Baillon  S. Calchi Novati  B. J. Carr  M. Crézé  Y. Giraud-Héraud  A. Gould  Ph. Jetzer  J. Kaplan  E. Kerins  S. Paulin-Henriksson  S. J. Smartt  C. S. Stalin  Y. Tsapras  M. J. Weston 《Monthly notices of the Royal Astronomical Society》2005,357(1):17-37

  相似文献   

VLBI观测信号相关处理中的小波保角变换     

XIA Haibo 《中国科学院上海天文台年刊》2004,(1)

Daubechies小波可以表征为幂函数或e指数函数的形式 ,保持相关相位条纹的幅角不变。在VLBI观测信号相关处理过程中引入了小波分析方法 ,以探讨小波理论在VLBI技术中的应用特点。两个台站的VLBI观测信号经过时间补偿和干涉条纹旋转后 ,利用静态小波算法在线性空间中的保角变换特征可提取VLBI信号的干涉相位特征 ,并完整保留相位的时序关系。  相似文献   

Environmental change and cultural response between 8000 and 4000 cal. yr BP in the western Loess Plateau,northwest China     

ChengBang An  Zhaodong Feng  Lingyu Tang 《第四纪科学杂志》2004,19(6):529-535

Two ancient swamps in the western Loess Plateau, northwest China record the climate history between 8000 and 4000 cal. yr BP. Grain size, CaCO₃, organic matter, mollusc fauna and pollen assemblages show that climate was wet between 8300 and 7400 cal. yr BP, distinctly humid and warm between 7400 and 6700 cal. yr BP, semi‐humid from 6700 to 6300 cal. yr BP, and semi‐arid between 6300 and 4000 cal. yr BP. The temporal and spatial distribution of archaeological sites shows that the prosperity of the neolithic cultures in the western part of the Chinese Loess Plateau did not appear until the climate changed to semi‐arid, implying that the semi‐arid climate was more favourable than wet and humid climate to neolithic peoples, whose subsistence was based on cereals adapted to arid environments. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

The Two Mini-lobes of the CSO OQ208—— VLBI Observations at 5 GHz and 8.4 GHz     

Wei-Hua Wang  Xiao-Yu Hong  Tao AnShanghai Astronomical Observatory  Chinese Academy of Sciences  Shanghai  National Astronomical Observatories  Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2003,3(6):505-512

We present the results of VLBI observations at 5 GHz and 8.4 GHz of the compact symmetric object (CSO) OQ208. Images taken on four epochs at 5GHz and one at 8.4GHz show that the parsec radio structure of the source consists of two mini-lobes, both of them are resolved into two hot-spots. We note that the component D is stronger than the component C in the south-west region at 5 GHz, indicating that component D is less free-free absorbed than C at low frequency. On the basis of the separation of components A and D, a proper motion of 0.032±0.02 mas yr~(-1) between the two mini-lobes is estimated. This value is about half the previous estimates based on the separation of components A and C with 8.4 GHz VLBI data. The reason for the decrease in the expansion velocity is discussed.  相似文献   

Resolving the pulsations of the subdwarf B star KPD 2109 + 4401     

A.-Y. Zhou  M. D. Reed  S. Harms  D. M. Terndrup  D. An  S. Zola  K. D. Gazeas  P. G. Niarchos  W. Ogloza  A. Baran  G. W. Wolf 《Monthly notices of the Royal Astronomical Society》2006,367(1):179-185

We present the results of extensive time-series photometry of the pulsating subdwarf B star KPD 2109 + 4401. Our data set consists of 29 data runs with a total length of 182.6 h over 31 d, collected at five observatories in 2004. These data comprised high signal-to-noise ratio observations acquired with larger telescopes and wider time-coverage observations obtained with smaller telescopes. They are sufficient to resolve the pulsation structure to 0.4 μHz and are the most extensive data set for this star to date. With these data, we identify eight pulsation frequencies extending from 4701 to 5481 μHz, corresponding to periods of 182–213 s. The pulsation frequencies and their amplitudes are examined over several time-scales with some frequencies showing amplitude variability.  相似文献   

The Kiloparsec-scale Structure of 3C 286     

Tao An  Xiao-Yu Hong  Wei-Hua WangShanghai Astronomical Observatory  Chinese Academy of Sciences  Shanghai  National Astronomical Observatories  Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2004,4(1):28-36

We present radio images of the compact steep spectrum (CSS) quasar 3C 286 acquired with the Very Large Array (VLA) at 8.4 and 22.5 GHz. The source exhibits a two-sided core-jet structure with a bright central component and two extended components one to the east (P.A. 100°) and another to the southwest (P.A. - 116°). From the compact core, an extension runs towards the southwest component up to - 0.7 arcsecond. The emission between the primary central component and the southwest component exhibits a knotty structure. A gradual change of the jet position angles from -135° to -120° in the inner southwest jet suggests a local bend. The position angle changes of the major eastern components E2 and El suggest that the eastern jet likely follows a curved trace. The bends in the jet trace may be associated with a relativistic precession or some interaction between the jet and the ambient matter. A mean spectral index of a22.58.4 - -0.76 (Sv ∝ va) is estimated for the core component. Steep spectra are also  相似文献